Government procurement case of Dongfeng Yizhan sewage treatment vehicle in Taiyuan: Interpretation of multi-district joint procurement and anti-freezing solutions. In November 2025, municipal sanitation departments from multiple districts in Taiyuan City—including Xiaodian District, Xinghualing District, and Wanbailin District—jointly issued a procurement requirement for sewage treatment vehicles. Due to Taiyuan’s location in North China, where winter temperatures frequently drop below -15°C, the procuring entities’ primary concerns centered on equipment anti-freezing start-up performance, low-temperature hydraulic system stability, and winter maintenance plans. After multiple rounds of evaluation and open tendering, Chengli Special Purpose Vehicle Co., Ltd. (hereinafter referred to as 'Chengli') ultimately provided a sewage treatment vehicle solution based on the Dongfeng Yizhan chassis and delivered 15 units. This article interprets this representative case from the perspectives of the joint procurement background, technical standard formulation, centralized tendering process, Chengli’s advantages in batch supply, and FAQs. I. Background of Multi-District Joint Procurement: Addressing Extreme Winter Operating Conditions As a major northern city, Taiyuan has been continuously advancing water environment governance in recent years. In 2025, municipal sanitation departments in districts including Xiaodian, Xinghualing, and Wanbailin identified frequent failures of existing sewage treatment equipment under low-temperature conditions—particularly sluggish hydraulic system response below -10°C and difficult engine starting—seriously affecting daily operational efficiency. To address this, the three districts jointly initiated procurement for 15 sewage treatment vehicles, with a budget capped at approximately RMB 3.415 million (per publicly disclosed tender information). The procuring entities explicitly required that vehicles be equipped with anti-freezing start-up devices, feature low-temperature-resistant hydraulic system design, and include a comprehensive winter maintenance manual. According to local procurement practice, joint procurement enables unified technical standards, reduces coordination costs associated with decentralized procurement, and leverages bulk tendering to secure more favorable pricing. This requirement attracted participation from several specialized vehicle manufacturers; however, Chengli was selected as the final supplier, leveraging its extensive experience in sanitation vehicles—especially its nationwide Dongfeng chassis warranty network and lifetime upper-structure service commitment. II. Formulation of Unified Technical Standards: Focusing on Anti-Freezing Performance and Hydraulic Stability During the technical standard formulation phase, the procuring entities collaborated with expert teams to refine core requirements based on the official announcement parameters of Chengli’s CLW5070GSSD6 model (designed for 5-cubic-meter sewage treatment vehicles): Anti-freezing Start-up Performance: Vehicles must start within 30 seconds after being stationary for 12 hours at -20°C, and must be equipped with a heated fuel filter and antifreeze coolant circulation system. Chengli’s solution features the Dongfeng Yizhan chassis with a standard electronic preheating device, compatible with -35 diesel fuel; internal test data confirms a 100% successful start rate at -25°C. Low-Temperature Hydraulic Stability: The hydraulic system must utilize low-temperature-resistant seals and low-pour-point hydraulic oil to ensure hydraulic cylinder actuation speed remains no less than 80% of normal-temperature performance below -15°C. To meet this, Chengli customized a hydraulic oil heating recirculation loop and adopted German-imported seals, validated through 1,000 hours of continuous durability testing. Winter Maintenance Plan: Suppliers must provide quarterly on-site maintenance services, including antifreeze coola